<template>
  <div class='xtx-carousel' @mouseenter="stop" @mouseleave="start">
    <ul class="carousel-body">
      <li class="carousel-item" :class="{fade:index===currentIndex}" v-for="(item,index) in sliders" :key="item.id">
        <slot :item="item">
          <RouterLink to="/">
            <img
              :src="item.imgUrl"
              alt="">
          </RouterLink>
        </slot>
      </li>
    </ul>
    <a href="javascript:;" class="carousel-btn prev" @click="aClick(-1)"><i class="iconfont icon-angle-left"></i></a>
    <a href="javascript:;" class="carousel-btn next" @click="aClick(1)"><i class="iconfont icon-angle-right"></i></a>
    <div class="carousel-indicator">
      <span v-for="i in sliders.length" :key="i" @mouseenter="currentIndex=i-1"
            :class="{active:i===currentIndex+1}"></span>
    </div>
  </div>
</template>

<script>
/*
*   轮播图
*   移入小点点实现切换
*   左右点击切换
*   自动切换
*   鼠标移入停止自动切换，移除继续自动切换
*   自动切换功能需要可以配置参数进行控制
* */
import { onUnmounted, ref, watch } from 'vue'

export default {
  name: 'XtxCarousel',
  props: {
    //轮播图
    sliders: {
      type: Array,
      default () {
        return []
      }
    },
    //  自动切换的时间间隔
    duration: {
      type: Number,
      default: 1000
    },
    //  是否开启自动播放
    autoPlay: {
      type: Boolean,
      default: true
    }
  },
  setup (props) {
    // console.log(props)
    // 当前圆点下标
    const currentIndex = ref(0)

    //左右点击按钮
    function aClick (n) {
      currentIndex.value += n
      if (currentIndex.value >= props.sliders.length) {
        currentIndex.value = 0
      } else if (currentIndex.value <= -1) {
        currentIndex.value = props.sliders.length - 1
      }
    }

    //保存定时器id
    let timerId = null

    //开启自动切换
    function start () {
      clearInterval(timerId)
      timerId = setInterval(() => {
        aClick(1)
      }, props.duration)
    }

    // 关闭自动切换
    function stop () {
      clearInterval(timerId)
    }

    //监听autoPlay变化
    watch(() => props.autoPlay, (newVal, oldVal) => {
      if (!newVal) return stop()
      start()
    },{immediate:true})
    //组件销毁清除定时器
    onUnmounted(()=>{
      clearInterval(timerId)
    })
    return {
      currentIndex,
      aClick,
      start,
      stop
    }
  }
}
</script>
<style scoped lang="less">
.xtx-carousel {
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;

  .carousel {
    &-body {
      width: 100%;
      height: 100%;
    }

    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;

      &.fade {
        opacity: 1;
        z-index: 1;
      }

      img {
        width: 100%;
        height: 100%;
      }
    }

    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;

      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0, 0, 0, 0.2);
        border-radius: 50%;
        cursor: pointer;

        ~ span {
          margin-left: 12px;
        }

        &.active {
          background: #fff;
        }
      }
    }

    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0, 0, 0, .2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;

      &.prev {
        left: 20px;
      }

      &.next {
        right: 20px;
      }
    }
  }

  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
</style>
